| 摘要 |
PROBLEM TO BE SOLVED: To readily and with excellent reliability ensure a contact area between a plug and an upper layer wiring layer even if the upper layer wiring layer is formed in border-less structure, in a semiconductor device of a multilayer wiring structure in which upper and lower wiring layers formed across an interlayer oxide film are connected to each other via the plug. SOLUTION: After a connection hole 13 is formed in an interlayer oxide film 12 via a Ti film 14a as a barrier metal layer 14, a tungsten film 1 5a is embedded in the connection hole 13 to be formed on the entire surface, and thereafter by a CMP processing using a slurry containing a hydrogen peroxide solution at concentration 0.5 to 2.0%, the tungsten film 15a is removed and left behind only in the connection hole 13 to form a plug, and next the interlayer oxide film 12 is removed by wet-etching by use of a fluorine-based solution at a predetermined thickness, so that an upper part of the plug 15 is projected, and a plug surface area is enlarged so as to come into contact with an upper layer wiring layer 16.
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